1. Technical Field
The present invention relates to a guiding device using a directional speaker that is capable of reproducing a sound having a very high directivity and a method of controlling the same.
2. Related Art
As information apparatuses are being developed and their uses are becoming widely spread, it is common to hear a multitude of sounds from various information apparatuses, especially, in public areas. However, unwanted sound or announcements cause confusion and discomfort to people who do not wish to hear the sound and announcements, and it becomes a cause of stress. Therefore, in public areas, it is highly desirable to reduce noise in the neighboring area, and improve the environment in theses area in terms of sound. For example, if voice information for advertisement or announcements is provided only in a specific area (area on-demand), the reduction of the noise in the neighboring area and the improvement of the effectiveness of announcements can be expected.
Generally, there are two purposes for voice guidance or audio advertisement. One is to provide advertising information to a targeted audience or in a specific area (private information), and the other is to announce them in a relatively wide area (public information).
In the former case, a directional speaker that is capable of reproducing high directivity sounds, such as an ultrasonic speaker (see, JP-A-2002-204492), has been receiving much attention. The ultrasonic speaker outputs a modulated signal that is modulated from an ultrasonic carrier wave by an audible acoustic signal, and thus is capable of reproducing high directivity sounds. Therefore, the ultrasonic speaker can be used for a local announcement such as a tour guide in an art museum.
Further, recently, a guide robot that changes guide (supplying) information (contents) according to a situation has been suggested (see JP-A-7-295637).
However, speakers used in a guiding device or a robot according to the related art function as the directional speaker or the loudspeaker, not both functions. Further, even though both the directional speaker and the loudspeaker can be mounted therein, in such a case, the size of the speakers and a system for dividing driving circuits and the speakers becomes larger, which consequently increases the manufacturing cost.